The present invention relates to a starter for a gas discharge lamp, and more particularly, to a starter assembly having a magnetic switch and control circuit used to start a gas discharge lamp.
The present invention relates to starters for gas discharge lamps, and in particular to a starter assembly having a magnetic switch for starting a lamp. Traditionally, gas discharge lamps used a special starter switch mechanism to start the lamp. When the lamp is first turned on, electricity flows through a bypass circuit and across a starter switch and through the lamp electrodes. This electricity preheats the electrodes, ionizing the gas in the lamp, thereby creating an electrically conductive medium. After the electrodes are heated sufficiently, the starter switch opens, causing the lamp ballast to provide a voltage surge, and the electric current to arc through the gas discharge lamp. The conventional starter switch uses a small discharge bulb containing neon or some other gas. The bulb has two electrodes positioned adjacent to each other. Current arcs between the electrodes, causing a small amount of heat to build within the bulb, which causes one bimetallic electrodes to bend so that it makes contact with the other electrode. When the two electrodes make contact, the current no longer arcs between the electrodes. Consequently, there are no charged particles flowing through the gas. Without the heat from the charged particles, the bimetallic electrode cools, bending away from the other electrode. This opens the circuit, causing the ballast to transfer energy to the lamp electrodes, and subsequently causing the lamp to ignite. When the current flows through the bypass circuit, it establishes a magnetic field in part of the lamp ballast. This magnetic field is maintained by the flowing current. When the starter switch is opened, the current is briefly cut off from the ballast. The magnetic field collapses, which creates a sudden jump in current causing the ballast releases its stored energy and light the gas discharge lamp.
Other gas discharge lamps rely on a design that does not include a starter switch. Instead, the lamp""s ballast constantly channels current through both electrodes. This current flow is configured so that there is a charge difference between the two electrodes, establishing a voltage across the lamp.
Alternatively, gas discharge lamps may rely on a high initial voltage to the lamp electrodes, producing a corona discharge used to start the lamp. Excess electrons on the lamp electrode surface forces some electrons into the gas. These free electrons ionize the gas, and almost instantly the voltage difference between the electrodes establishes an electrical arc.
A first problem with the above starter designs is that they are unable to accommodate variations in lamp preheat requirements. A particular starter must be designed for the preheat requirements of a particular gas discharge lamp or narrow range of gas discharge lamps. A second problem with the above starter designs is that they are unable to adapt to variations in gas discharge lamps caused by variations in lamp materials and lamp construction. These variations can cause a change in the preheat requirements for the lamp. This change may result in a change in the lamp starter design, or a discarding of off-specification lamps. Another problem with the above starter designs is that they are unable to accommodate changes in gas discharge lamp preheat requirements, particularly as these gas discharge lamps change with use and age. The starter assembly of the present invention overcomes, or minimizes these, and other problems associated with conventional gas discharge lamp starters.
The present invention comprises a unique starter assembly for a gas discharge lamp. The starter assembly includes a current path with a first leg connected to a first electrode of a gas discharge lamp, and a second leg connected to a second electrode of the gas discharge lamp. The current path comprises an magnetic switch. The magnetic switch is actuated by an electromagnet controlled by a control circuit. The control unit may be programmed with the preheat time required for the gas discharge lamp. In an alternative embodiment, the control unit may be programmed with a range of preheat times for a gas discharge lamp. According to this embodiment, the control unit may be provided with preheat times that increase in duration with each start of the lamp or in the alternative, increase in duration as the lamp ages.
In another alternative embodiment, the starter assembly is further comprised of a control unit and a radio frequency identification system. The radio frequency identification system includes a transponder coupled with the gas discharge lamp. The radio frequency identification system obtains information about the lamp from the lamp transponder. This information is then provided to the control circuit. The control circuit may modify the preheat time for that lamp based on this information. Those skilled in the art would recognize that alternative non-contact, as well as contact-type identification systems may be used instead of the radio frequency identification system.